Carried by History: Cesar Lattes, Nuclear
Emulsions, and the Discovery of the Pimeson
Cássio Leite Vieira & Antonio Augusto
Passos Videira
Physics in Perspective
ISSN 1422-6944
Volume 16
Number 1
Phys. Perspect. (2014) 16:3-36
DOI 10.1007/s00016-014-0128-6
1 23
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Phys. Perspect. 16 (2014) 3–36
2014 Springer Basel
1422-6944/14/010003-34
DOI 10.1007/s00016-014-0128-6
Physics in Perspective
Carried by History: Cesar Lattes, Nuclear
Emulsions, and the Discovery of the Pi-meson
Cássio Leite Vieira* and Antonio Augusto Passos Videira**
We analyze the role played by the Brazilian physicist Cesar Lattes (1924–2005) in the
historical development of the nuclear emulsion technique and in the co-discovery of the
pion. His works influenced and gave impetus to the development of experimental physics in
Brazil, the foundation of a national center dedicated to physics research, the beginnings of
Brazilian ‘‘Big Science,’’ and the inauguration of a long-lasting collaboration between Brazil
and Japan in the field of comic ray physics.
Key words: Cesar Lattes; Gleb Wataghin; Giuseppe Occhialini; Cecil F. Powell;
Eugene Gardner; nuclear emulsion technique; mesons; Mount Chacaltaya; history
of elementary particle physics; history of physics in Brazil.
Understanding Brazilian Physics
Cesare Mansueto Giulio Lattes (1924–2005)—known simply as Cesar Lattes in
Brazil or Giulio Lattes among colleagues and friends abroad—is to date certainly
the most famous Brazilian physicist, theoretical or experimental. His fame goes
beyond Brazil’s borders, reaching other Latin-American countries. In Bolivia, he
was instrumental in establishing an international collaboration that led to building
the still-active Cosmic Physics Laboratory at Mount Chacaltaya. In Argentina, his
late 1940s research was adduced by the Austrian physicist Guido Beck
(1903–1988) in order to convince young Argentinean physicists that they too could
do high-level science like their Brazilians colleagues, then headed by the RussianItalian physicist Gleb Wataghin (1899–1986).
* Cássio Leite Vieira is the International Editor of Ciencia Hoje magazine, published by the
Ciencia Hoje Institute in Rio de Janeiro. He has a PhD in History of Science from the
Federal University of Rio de Janeiro (2009) and has been carrying out research on the
history of nuclear emulsion technique and on the history of physics in Brazil.
** Antonio Augusto Passos Videira is Associate Professor of Philosophy of Science at the
State University of Rio de Janeiro, has a PhD in Epistemology and History of Science from
the Université Paris VII (1992), is Researcher of the National Council for Scientific and
Technological Development (CNPq), and is a Collaborator at the Brazilian Center for
Physics Research, in Rio de Janeiro.
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Some of Lattes’ fame owes to his participation in experiments that proved the
existence of the pi-meson, a particle theoretically proposed in 1935 by the Japanese physicist Hideki Yukawa (1907–1981) and which contributed to the birth of
elementary particle physics. In Brazil, the media elevated Lattes to the status of a
hero. His deeds were advanced by his fellow scientists in a political campaign
aiming to improve the institutional conditions of their work (teaching and
research)—low wages and a lack of well-equipped laboratories were the general
rule in the country in the years that followed the Second World War. As a result of
that political campaign—which also included intellectuals, artists, politicians,
journalists, industrialists, military personnel, among others—new research centers
were created or renovated, and the foundations of a political and administrative
infrastructure at the federal level were laid. A decade after the discovery of the pi
meson, Lattes was again instrumental in initiating a scientific collaboration in the
field of cosmic rays with Japanese physicists led by Yukawa. The so-called CBJ
(Brazil-Japan Collaboration), also located at Mount Chacaltaya, carried out
research for the following 30 years or so.
Before we can understand the ‘‘Lattes phenomenon’’—how he came to be so
dubbed by the pioneer of science journalism in Brazil José Reis—it is first necessary to have at least a cursory understanding of the history of physics in Brazil.1
From the discovery of Brazil in April 1500 to almost the end of the nineteenth
century, practically no physics was done in the country, with a few exceptions, such
as expeditions to collect meteorological and astronomical data and the building of
an astronomical observatory in Olinda (northeastern Brazil) in the seventeenth
century. Yet these and other such initiatives seem not to have had enough influence to radically change the environment or mentality at the time with regard to
science.2
Change came in 1808, when the Portuguese royal family moved to Brazil.
Infrastructure had to be put in place to make Rio de Janeiro—suddenly the capital
of a vast overseas empire—capable of training the human resources needed to
maintain order throughout the Portuguese empire in medicine, engineering,
defense, public services, etc. New institutions were founded, including the
National Library, the Royal Gardens (later the Botanic Gardens), the Royal
Museum (later the National Museum), the Naval Guards Academy, the Medical
and Surgical College of Bahia, and the Medical and Surgical School of Rio de
Janeiro.
The first theoretical physics in Brazil dates back to the late 1800s, mostly at the
schools of engineering in São Paulo and Rio de Janeiro. Theoretical physics is
cheap and basically just needs an objective, a brain, some paper, a pen (or pencil),
and some scientific periodicals and books. Theory can therefore be pursued in
environments that provide little in the way of support for science, as was the case
in Brazil in the early twentieth century. Meanwhile, experimental physics in Brazil
was late to begin, except for Henrique Morize’s work on X-rays in the 1890s,
shortly after their discovery by Wilhelm Roentgen.3
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Only at the end of the nineteenth century were laboratory practices—including
physics—introduced to Brazil’s schools of engineering, such as the ones in Rio de
Janeiro (1875), Ouro Preto (1875), São Paulo (1893) and Porto Alegre (1896).4 In
that century a movement for ‘‘pure science’’ emerged, mostly driven by university
teachers. A prime leader of this movement was Morize (1860–1930), who in 1898
defended his thesis and conducted experiments on cathode rays and X-rays at the
Rio de Janeiro Polytechnic. This movement led to the founding of the Brazilian
Society of Science in 1916, which a few years later became the Brazilian Academy
of Science. It is interesting to note how a society, apparently open to all, or so it
would seem from the discourse during the movement that led to its creation,
became an academy for the few; the historiography of science in Brazil has yet to
provide a satisfactory explanation for this.5
In the 1920s, when European physicists were forging the theoretical bases for
quantum mechanics and experimenting and discussing the profound philosophical
implications of this theory, in Brazil experimental physics was represented by little
more than one teaching laboratory—incidentally, modernized by Morize himself—at the Rio de Janeiro Polytechnic.6 Beside that, the German-born Brazilian,
Bernhard Gross, did some experiments at the Institute of Technology (now the
National Institute of Technology) from 1933 to 1938.7 The situation was certainly
no different in many countries on the periphery of the scientific revolution.
The state of physics research in Brazil changed significantly in the 1930s with
the founding of the University of São Paulo in 1934 and, to a certain extent, of the
University of the Federal District in Rio de Janeiro in 1935, although this institution was shut down just three years later by the Getúlio Vargas (1882–1954)
government for political reasons.8
Cesar Lattes was a product of the University of São Paulo and the changes that
had taken place in physics in Brazil during the 1930s. Italian-Russian physicist
Gleb Wataghin went to work at the University of São Paulo, where he began a
theoretical and experimental research program. He was joined by a number of
young physicists, including Marcello Damy de Souza Santos (1914–2009), Mário
Schenberg (1914–1990), Paulus Aulus Pompeia (1911–1993), and, a little later,
Oscar Sala (1922–2010).9
With the exception of a few sporadic experiments, experimental physics in
Brazil only took off with the arrival of Wataghin in the 1930s. Originally from
Turin and appointed by Enrico Fermi—who in 1938 would become a Nobel
Laureate in Physics—Wataghin, despite his theoretical background, invested in
experimental physics. The detection of showers of penetrating particles by Damy,
Pompeia, and himself were the first findings in Brazil to have international
repercussions.
This earliest Brazilian experimental physics was still modest in terms of the
equipment used. The experimental physics scene in the country only changed with
the impact of Lattes’s work abroad. In Brazil, a movement headed by the theoretical physicist José Leite Lopes, a colleague of Lattes, started to take shape. It
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galvanized not just scientists, but also businessmen, artists, journalists, and military
men who hoped that Brazil might master nuclear energy both for peaceful and
military purposes, at the time when nuclear physics was the big attraction of
science.9
Such were the roots of the founding of CBPF in early 1949, which, for political
reasons, was conceived as a private foundation rather than being part of a university.10 In the wake of CBPF came the National Research Board (Conselho
Nacional de Pesquisas), today the National Board for Science and Technology
Development (Conselho Nacional de Desenvolvimento Cientı́fico e Tecnológico,
or CNPq). A good part of the political and administrative framework for the science produced in Brazil in the following years can be ascribed to this movement.
From the late nineteenth century to the 1930s, in the absence of any government policy the norm remained isolated initiatives in the area of physics pursued
by university professors who wrote and published articles, mostly of a theoretical
nature. These were individual endeavors, including: 1) the work of Joaquim Gomes de Souza, better known as Souzinha (1829–1864), on mathematical physics;11
2) the introduction to Brazil by Manoel Amoroso Costa (1885–1928) of Einstein’s
theory of relativity at the beginning of the 1920s;12 3) the first works in Brazil by
Theodoro Ramos (1895–1936) on the old quantum theory;13 4) and the work of
Bernhard Gross (1905–2002), a German who settled in Brazil, on cosmic rays in
the early 1930s.14
Isolated and insignificant though these contributions may have been in terms of
their contribution to international physics, they were nonetheless important
because they helped to change the prevailing mindset, creating, to a greater or
lesser extent, an environment that was propitious for the introduction of scientific
research to Brazil.
Brief Biography
Lattes was born in Curitiba on July 11, 1924. His first years of schooling were with
a private teacher in Porto Alegre; he later spent six months at the Menegapi
Institute in the same city. His father, Giuseppe Lattes, originally from Turin, had
migrated to Brazil in 1912. When the First World War broke out, however, he
went back to Italy—as did many Italians living in Brazil—and fought there as a
member of the Alpine troops, engaged in battle particularly against the Austrians.
At this time he met Carolina Maroni, from the Italian province of Alessandria.
They married and in 1921 moved to Brazil and set up home in Curitiba, where
Lattes studied at the American School. After the 1930 revolution, the family
(figure 1) spent six months in Italy, where Lattes attended a state school in Turin
for three months. The family then moved to São Paulo, where Lattes studied at
Dante Alighieri high school from 1934 to 1938.15
Lattes’s father worked as a manager with the French Italian Bank in São Paulo,
where Wataghin had an account. He told the European physicist that his son,
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Fig. 1. Lattes (left), his brother and parents. Credit: Acervo Cesar Lattes/SIARQ/Unicamp.
Cesare, had a liking for numbers and science and Wataghin asked him to pay a
visit.16 Lattes enrolled in the physics course at the University of São Paulo and
graduated—the only physicist in his class—in 1943, at the age of 19, because the
legislation at the time allowed school years to be skipped. He then started to work
as an assistant to Wataghin, Schenberg, and Walter Schutzer (1920–1963) in their
theoretical work (figure 2).17 Shortly afterwards, frustrated by the complications of
this line of research, he gravitated towards experimental physics.
At this time, a person who became an important catalyst in Lattes’s life comes
into play: Giuseppe Occhialini (1908–1993). This Italian physicist had come to
Brazil in 1937 on the invitation of Wataghin. In fact, Wataghin had been asked to
extend this invitation by Occhialini’s father, the director of the Institute of Physics
in Genoa, because he feared for the safety of his son, an anti-fascist, under
Mussolini’s rule.18
Occhialini worked for a time with Wataghin at the University of São Paulo.
When Brazil joined the war, Occhialini found himself forced to take refuge in
Itatiaia National Park, which straddles the states of Rio de Janeiro and Minas
Gerais. He returned to the university around 1944, when he gave a course on
X-rays with the idea of earning some money to return to Europe and fight the
fascists. Only one student enrolled for the course: Lattes. So Occhialini simply
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Fig. 2. Wataghin (second from the right) and collaborators; Occhialini is the third from the left.
Credit: Acervo Instituto de Fı́sica/USP.
ditched the theoretical part—not something that particularly interested him—and
put his student to develop films exposed to radiation and measure the physical
properties of the events they recorded. It is quite possible that Lattes’s interest in
experimental physics was first awakened at this time.19
Occhialini returned to Europe before the end of the Second World War. He
had given up his idea of fighting the fascists, having been warned by colleagues
that his family, who lived in Italy, could be the target of reprisals. Occhialini went
to England in 1944, where, having been thoroughly vetted by the British government, he was sent to work with Cecil Frank Powell (1903–1969) at the H.
H. Wills laboratory at the University of Bristol, where research was geared
towards military applications. Powell was a pacifist and had socialist tendencies.20
At the time, even though young (around 30 years of age), Occhialini was
already an internationally renowned physicist because he had participated in the
discovery of the positron in the early 1930s in England, together with Patrick
Blackett (1897–1974), who went on to win the Nobel Prize for this discovery. In
fact, something that stands out in Occhialini’s biography is that on two occasions
this prize eluded him (Blackett in 1948 and Powell in 1950).21
In Brazil, Lattes started to devote himself to experimental physics involving
cosmic rays with two colleagues: Wataghin’s son, Andrea (1926–1984), and Ugo
Camerini. Pooling their own resources, they set up a cloud chamber that Occhialini had brought to the country and left there. This equipment basically consists of
a recipient that contains water vapor in a supersaturated state—consequently, any
change to the temperature or pressure, however small, could turn the vapor into
liquid. When electrically charged particles go through this chamber, they alter this
fine equilibrium and make droplets form along their route. As Powell said, the
track of a particle looks like a pearl necklace. These tracks are photographed and
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their analysis indicates what kind of particle has gone through the container
(electron, proton, etc.). Lattes, Camerini and Andrea Wataghin were studying the
particles from the cosmic-ray showers that reached the earth and the cloud
chamber.22
At some point in 1945—probably towards the end of the year—Lattes received
a package in the mail from Occhialini containing special photographic plates with
the capacity to show particle tracks far more clearly than the cloud chamber.
Lattes was very excited by what he saw on the plates. He wrote to his former
teacher asking to go to Bristol to learn the technique there.
Occhialini managed to get a modest grant from Powell (just 15 pounds a
month), donated by Wills, a cigarette manufacturer—the same firm that had
financed the building of the H. H. Wills laboratory at the University of Bristol.
Meanwhile, Lattes managed to get help to pay for his passage from the Getulio
Vargas Foundation, thanks to the mediation and influence of Brazilian mathematician Leopoldo Nachbin (1922–1993). He embarked on the British ship ‘‘Saint
Rosario,’’ which, according to Lattes, was the first ship to take passengers from
Brazil to Europe after the Second World War.
Lattes was married to Martha Siqueira Neto (1923–2003), a mathematics
graduate from northeastern Brazil. Together they had four daughters and nine
grandchildren. Throughout his life Lattes received numerous awards in Brazil and
abroad. He became something of a mythical figure in Brazilian science, not unlike
Oswaldo Cruz (1872–1917) or Carlos Chagas (1878–1934).23
Plates for Physics
The special photographic plates Occhialini sent Lattes were the result of a technique that had taken about 45 years to be refined to that level. Or, to go even
further back, they were the outcome of almost 200 years of interaction between
physics and photography.24
Photography, like the airplane, had no single inventor but emerged from a sum
of contributions.25 Announced (almost simultaneously) in France and England in
1839, photography was the outcome of advances in physics and chemistry—atomic
theory, theories of heat and electromagnetism, the wave nature of light, etc.—and
also of currents in philosophical thinking at the time (Romanticism and positivism). Until 1850, leading scientists and scientific academies—especially in the UK
and France—helped to develop and disseminate the invention, and articles on
photography were published in the most prestigious scientific journals of the day.
But in the middle of the century, as photography started to take shape as a
profession, scientists retreated from this field, which was henceforth dominated by
these new professionals and by industry.26 For decades, scientific understanding of
photographic processes was left to professional photographers, who were in most
cases only amateur scientists. Theories about the photographic process abounded,
how light creates images from silver salts. The answer to this question only started
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to be elucidated in 1938, with the theory of the photographic process developed by
American physicist Ronald Gurney (1898–1953) and Briton Nevill Mott
(1905–1996).27
The use of photography by science came back with a vengeance in the late
1800s, when physicists and chemists used it to study the properties of what were
then new phenomena (X-rays, radioactivity, electrons and electromagnetic waves).
In this period, according to the analysis put forward by the historian Erwin Hiebert, physics had the following characteristics:
1)
2)
3)
4)
a growing perception that there was a single physics;
attempts to combine the very small with the very big;
a more relaxed posture towards scientific speculation;
increased collaboration between research groups.
This program, according to Hiebert, was put into practice according to the
following theoretical principles:
1)
2)
3)
conservation of energy;
respect for the order of the elements in the Periodic Table;
reverence for ideas about electromagnetism put forward by Scottish physicist
James Clerk Maxwell in the mid-nineteenth century.28
In its way, photography was part of this program. Even so, by the early 1900s it
was still seen as a mere detector of qualitative, but not quantitative, properties.
Experiments made by both Ernest Rutherford (1871–1937) and Polish physicist
Marie Curie (1867–1934) helped to reinforce this idea that it was a detector that
served merely for general analysis but not to quantify experimental results.29
Indeed, the technique employed in the 1940s by Powell, Occhialini, Lattes, and
other scientists in the research that led to the dual discovery of the pion only
became truly significant and potent when photography was combined with another
great invention, microscopy. This happened towards the end of the first decade of
the twentieth century, and, combined with a few recipients for chemicals for
development purposes, became responsible not just for discoveries in the area of
radioactivity, but also for nuclear and particle physics.
Finally, photography applied to physics—and the subsequent nuclear emulsion
technique—had been born. It was photography ? microscopy ? chemical reagents,
as Powell, Peter Fowler, and Donald Perkins defined it in a classic book on nuclear
emulsions. With these three lightweight, cheap ingredients, physicists made
groundbreaking science in the coming decades in practically every continent.30
From Photography to Nuclear Emulsions
From 1910 to 1917, around a dozen articles on radioactivity using photography
applied to physics appeared containing important discoveries and developments.
At the end of World War I, however, the method was practically forgotten and had
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to be rediscovered by several European physicists, including Austrian physicist
Marietta Blau (1894–1970) and several Soviet physicists.
Blau became one of the twentieth century’s most prominent experts in the
nuclear emulsion technique, which she started to work on at the Institute for
Radium Research in Vienna, where she and other women worked without any
financial compensation. In the 1930s, Blau was responsible for seminal discoveries
using emulsions. Alongside her compatriot, Hertha Wambacher, she developed
methods for seeing very fast protons: particles at high speed have little contact
with the silver salts, so they do not deposit much energy in the medium, making it
harder to see their tracks. Even more importantly, when normal photographic
plates were exposed at the altitude of the Jungfrau mountain in Austria, Blau and
Wambacher observed the disintegration of the nucleus of an atom caused by a
particle of cosmic radiation. This was the first such disintegration recorded on a
photographic plate.31
A Jew, Blau fled Nazi Vienna in 1938. She had fallen out with Wambacher, who
had joined the Nazi party in 1934. In exile, Blau spent time in many countries,
including Mexico and the United States, where, at Brookhaven National Laboratory, she conducted research into the use of nuclear emulsions as particle
detectors in accelerators.32 Blau and Wambacher’s results prompted Powell to
start his research using the photographic method, which were also instrumental in
the use of photography for particle detection by physicists working in the area of
cosmic rays.
Until then, physicists used the photographic plates sold commercially for blackand-white photography. These had a very fine layer of gelatin (around five thousandths of a millimeter thick) serving as a support for tiny grains of a lightsensitive silver salt (normally silver bromide), which was also sensitive to subatomic particles (electrons, positrons, protons, alpha particles, etc.)—hence their
scientific application. Scientists, however, preferred plates that had the gelatin
(and therefore the silver salt) deposited on a piece of glass because these were
easier to use under a microscope. To understand this preference, we should recall
that since the late 1800s, conventional photography used flexible films that could
be manufactured in rolls and inserted in cameras.
When a photon or an electrically charged particle goes through a grain of silver
bromide, it sets off a series of physical reactions that make this grain developable;
technically speaking, this chain of phenomena is what we call the photographic
process. With the right reagents, the grain exposed to light or a particle turns into a
‘‘cluster’’ of silver metal. Precisely these ‘‘dots’’ of silver form the image we can see
with the naked eye.
What interested physicists was the ‘‘tracks’’ left by subatomic particles. With the
help of microscopes, they investigated in detail the inside of the gelatin—the
marks left are rarely even one millimeter in length. By measuring their length, the
number of degrees subtended by the track, its width and other properties, they
managed to determine what type of particle had left each particular track. For
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around fifty years, physicists made extensive use of photography and microscopy
for such purposes. It was a long time before nuclear emulsions were fully accepted
and adopted by physicists. In the 1930s, the technique was still regarded with
skepticism by part of the physics community (mainly physicists working in the
nuclear area). It was believed that the method was not precise—in other words, it
was tarred with the same brush as photography had been at the turn of the century,
considered insufficiently precise for serious quantitative work33
This skepticism changed when cosmicists (the contemporary term for physicists
studying cosmic rays) decided to employ photographic techniques at the end of the
1930s, when industry took its first steps in the manufacture of plates with characteristics more suited to scientific work. The first experiments were now done
exposing photographic plates to cosmic radiation in balloons, redoing experiments
first performed without plates in the early 1910s, when the results had led to the
conclusion that the source of such radiation could only be extraterrestrial.34
One of the cosmicists working in the 1930s was Powell. His colleague Walter
Heitler, then in England, first drew his attention to the results obtained by Blau
and tried to repeat them. (Blau and Heitler had met previously in Germany.) The
experiments using photographic plates were promising. Throughout the war,
Powell had continued to use them to study subatomic particles, including experiments of interest to the British nuclear program. One of his main contributions
was keeping photographic techniques ‘‘alive’’ throughout the war period and
welcoming young physicists from different countries to his laboratory.
At the end of the war, the UK’s photographic industry, which had lost many
government contracts, decided to focus on a new market niche: the use of photographic plates by physicists. The country was lagging behind its peers in nuclear
physics and particle accelerator building so that it decided to set up two committees to address these problems: one for the construction of these machines
(Accelerator Panel) and the other for the development of special photography to
meet the needs of physicists in this detector (Photographic Emulsion Panel). These
panels had representatives from industry, universities, and the British nuclear
establishment.35
Two companies—first Ilford, shortly followed by Kodak—perceived in this
interface with science an opportunity to expand or at least to maintain their
market share. Meanwhile, physicists needed a reliable particle detector and the
nuclear establishment was hoping for some defense-related application—which
never happened.
Basically, the physicists wanted these new photographic plates to have two
features that commercial plates did not have:
1)
2)
a layer of gelatin of 50 to 100 thousandths of a millimeter thick—that is, 10 to
20 times thicker than a normal plate;
four times more silver bromide, enabling subatomic particles to expose more
grains as they crossed the gelatin, leaving tracks with more black dots, making
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Cesar Lattes, Nuclear Emulsions, and the Discovery of the Pi-meson 13
it easier to calculate the size of the track and therefore the energy of the
particle, hence making them easier to identify.36 These new plates were called
nuclear emulsions and so the photographic method applied to physics came to
be called the nuclear emulsion technique.
Shortly after the first meetings of the Photographic Emulsion Panel (to which
Occhialini made important contributions, even though his participation was barred
because he was Italian), Ilford set off in the lead—probably because of a patent
that enabled it to increase the quantity of silver bromide in the gelatin—and
produced the first new plates, which were promptly tested by Powell and other
physicists and chemists. Developed and observed under a microscope, the new
plates yielded surprising revelations. It was probably one of these plates, from the
first batch, that made its way to the young Lattes in Brazil.
Lattes in Bristol
In early 1946, Lattes disembarked in Liverpool and travelled on to Bristol. His
plan was to learn nuclear emulsion techniques and use them in the study of cosmic
rays, though his work at the H. H. Wills laboratory began far more modestly. His
first job was to study the radioactivity of the chemical element samarium—an
experiment whose only importance was that it gave him practice with the
technique.37
Shortly after his arrival, Lattes and other younger members of the laboratory—
Peter Fowler (1923–1996) and Pierre Cüer—were entrusted with an important
task: to calibrate the latest batches of nuclear emulsions. All detectors have to be
calibrated, and in the case of nuclear emulsions this meant basically knowing the
length of the track and the number of grains exposed. With that information, it
would be possible to distinguish the track of one particle (e.g. a proton) from that
of another (e.g. an alpha particle, which is heavier, made of two protons and two
neutrons). As he was planning these calibration experiments, done in the particle
accelerator at Cambridge, Lattes had the idea of adapting nuclear emulsions so
they could be used to study cosmic rays. At this point, by Lattes’s own admission,
one of his great contributions to physics came about: he telephoned Ilford and
ordered a batch of emulsions with the addition of boron to the gelatin—an element which, in the form of borax, is used as an antiseptic in the pharmaceuticals
industry.*, 38
Lattes also had the idea of observing how a boron nucleus would disintegrate if
it were hit by another nucleus (a deuteron, the nucleus of deuterium, also known
* Some additional historical contextualization is needed here: in many statements, Lattes
said he believed this was the first time boron was added to photographic plates. In fact, H.J.
Taylor and Maurice Goldhaber, working together in Cambridge (UK), had done this in the
1930s, but with the purpose of studying nuclear reactions involving the boron nucleus and
neutrons, then recently discovered.
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as heavy hydrogen) accelerated in the Cambridge accelerator. He found that the
collision would split the nucleus into a carbon nucleus and a neutron. It was this
neutron that interested him. His idea was to study neutrons generated in the
cosmic-ray shower by means of a kind of inverse reaction: upon exposing the
nuclear emulsions to cosmic rays, with any luck a neutron may collide with a boron
and produce fragments (two alphas and one tritium, each composed of two neutrons and one proton) that, being electrically charged, would leave tracks in the
emulsions. By studying the properties of these products, Lattes would be able to
discover properties of these so-called cosmic neutrons.
In late 1946, Occhialini went on a skiing holiday in the French Pyrenees.
Lattes’s own statements and extant historical documentation indicate that he
asked his former teacher to expose the nuclear emulsions with and without
boron on Pic du Midi, at an altitude of some 2,800 meters.39 This collaboration
between Lattes and Occhialini changed the course of the work at H. H. Wills,
which at the time was a far cry from anything that could be described as cuttingedge. As Lattes said, Powell was still doing conventional physics—making protons collide with neutrons in accelerators—using the old photographic plates
(probably Ilford half-tones) rather than the new ones from the same company
(now called nuclear emulsions).
Back from his holiday, Occhialini—whose creativity in the realm of experimental physics was only matched by his aversion to complex mathematical
theories—developed the batches of nuclear emulsions. He was surprised by what
he saw on the batch containing boron: there was a veritable web of tracks never
before been seen in any experiment. These findings were quickly reported in an
article sent for publication in Nature in early 1947. (It is likely that the observations were made in late 1946.)40
What matters here are the names attached to the article: Occhialini and Powell
(figure 3), the latter, according to Lattes, being completely unaware of what had
been done. In his own words, Occhialini, perceiving there was something quite
new in the emulsions with boron exposed on Pic du Midi, decided not to pass on
the article for approval by Powell, who was known to be a stickler for good writing,
which sometimes delayed publications by months. Apparently, once when he went
on holiday, Powell had hired a poet friend to oversee the writing of articles at H.
H. Wills, which, in the words of a witness (M.G.K. Menon), almost drove the
laboratory’s physicists mad.*
When Lattes saw his name was not on that first article, he complained to his
former professor, with whom he was able to converse fluently in Italian. Shortly
afterwards, an article was published about cosmic neutrons signed by Lattes and
Occhialini.41 These nuclear emulsions with boron revealed ‘‘a whole new world,’’
* Powell’s interest in literature in general and poetry in particular was well known by his
colleagues. Many, including Occhialini and Lattes, regarded him as a master of the spoken
word.
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Fig. 3. Cecil F. Powell. Credit: Nobel Foundation.
to quote Powell’s autobiography.42 At H. H. Wills, about a dozen women had the
job of examining the nuclear emulsions in detail under the microscope (figure 4),
looking for tracks that might reveal new fragments of matter—including the pimeson and/or the mesotron (to use the nomenclature of those times, before the
current terms pion and muon came into use).
In what follows, it is not known exactly when the events in question took place
because the dates of the accounts and documents are sometimes conflicting. In a
letter from 1990—decades after the facts—Fowler wrote that the events probably
took place towards the end of 1946, around October or November, when Occhialini returned from skiing in the Pyrenees,43 and that Powell, to verify what he and
his colleagues had on their hands, delayed publication by around three months.
One of Powell’s microscope observers, Marietta Kurz, found two V-shaped tracks,
one of which went beyond the edges of the emulsion, which the physicists called an
incomplete event. A few days later—and again, we do not know exactly how
many—two other tracks, this time L-shaped, were found by microscope observer
Irene Roberts, wife of physicist Max Roberts, who went on to make a career at
CERN.44
These new tracks formed a complete event, one that would make history
(figure 5). The shorter track was identified as being a pi-meson (Yukawa’s meson,
now called a pion) and the other a mesotron or mu-meson (now called a muon, a
heavier partner of the electron). The controversy that had existed for ten years—
are there one or two mesons?—and had galvanized great names in theoretical and
experimental physics seemed to have been resolved.45 Those tracks reproduced on
the few pages of the article signed by Lattes, Muirhead, Occhialini, and Powell in
Nature of May 24, 1947, demonstrate a very strong and prevailing feature of
science: the power of the image.46
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Fig. 4. A team of emulsion microscopists working at the Brazilian Center for Physics Research at
Rio de Janeiro (ca. 1960). Powell’s method of work was emulated by Lattes and colleagues in
Brazil. Credit: Centro Brasileiro de Pesquisas Fı́sicas/Ministério da Ciência, Tecnologia e
Inovação.
The Bristol group—as Lattes always stressed—was running against the clock
because a group from Imperial College, London, had already started to develop
photographic emulsions at high altitudes. But instead of mountains, from October
1946 on they started using Royal Air Force planes flying as high as 10,000 meters.
This ‘‘group’’ was really one young physicist, Donald Perkins—today, emeritus
professor at Oxford—working alone on nuclear emulsions and exposing them on
military airplanes while his supervisor, George Paget Thomson—son of the discoverer of the electron and also winner of the Nobel Prize in Physics (1937)—
showed very little interest in the matter.47
In January 1947 (before the work by the Bristol team just described), Perkins
had published an article that showed the disintegration of a nucleus by the
capture of a meson (as it turned out, a negative pion), whose energy is absorbed
there, causing the nucleus to be blasted apart. Because it was not possible to
establish with certainty from this single event that Yukawa’s particle had been
discovered, the generic term ‘‘meson’’ was therefore used at the time.48 But, in
the words of Lattes, with Perkins’s article, the amber light leading to the pion
had been lit, meaning that the Bristol group was afraid of losing to Perkins the
race for the discovery.49 Often in the history of science, primacy is hard to
identify clearly and often does not make sense, not least because it depends on
how the facts are interpreted. It is worth stressing here that one of the twentieth
century’s greatest names in nuclear emulsions, Marietta Blau, considered Perkins
to have discovered the negative pion and Powell’s team to have discovered the
positive pion.50
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Fig. 5. The track of a pion in a mosaic of emulsions from 1947. Note the signatures of Lattes,
Powell, and Occhialini. Credit: Personal archives of Alfredo Marques.
Reaching for the Heights
These two events were enough to demonstrate the existence of the pi-meson and
to differentiate it from the mesotron. But on their own they were not enough to
reveal key properties of the two particles, like their masses. More was needed.
Before the article was published in Nature, Lattes went to Bristol University’s
Department of Geography to find a higher peak where he could expose more
nuclear emulsions in the hope of capturing more pi-meson/mesotron pairs (or pimi, as they called them at the time). The higher the altitude, the greater the chance
of capturing particles from the cosmic-ray shower, which generally begins between
10 and 20 km above ground level. Lattes thought that Mount Chacaltaya, in
Bolivia, whose peak is around 5,500 m in altitude—almost twice the elevation of
Pic du Midi in the Pyrenees—would be suitable. Why not a mountain in Europe?
Decades later in an interview, Lattes said that ‘‘things were still tricky in Europe’’
because of the war. In other words, hard feelings had not yet abated.
Lattes went to Brazil and then embarked for Chacaltaya, where he exposed the
emulsions. One month later he returned to retrieve them. He developed one of
them in Bolivia and even though the water was not of good enough quality for this,
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he saw that he had a ‘‘big deal’’ on his hand. He returned to Brazil, sent a telegraph
to Powell with the good news, discussed the experiment with colleagues, and
returned to Bristol.51
Arguably the most important historical document from this time is the laboratory log Lattes used to record his observations of the hundreds of tracks he
found in the emulsions exposed in Bolivia. This documentation helps us to see that
the Bristol team found about 30 more pi-mesons disintegrating into muons
(complete decay) than the two pi-mi decays found earlier that year and published
in Nature. With this mass of events it was possible to calculate the ratio between
the masses of these two particles to show that one (the pion) was heavier than the
other (the muon). These results were published in Nature in October of that
year.52
Meeting Bohr
The news of the discovery of the pi-meson in Bristol came to the attention of
Danish physicist Niels Bohr. There is (indirect) historical evidence that Bohr sent
two young assistants—we hazard the guess that they were J. E. Hooper and M.
Scharff, physicists who later wrote a book on cosmic rays—to find out what was
going on at H. H. Wills. According to Lattes, when they got there they noticed that
the one who was ‘‘getting his hands dirty’’ was the Brazilian himself.53 Not long
afterwards Lattes received an invitation to give talks in Denmark and Sweden
about the results at Bristol. This would explain why such a young member of
Powell’s team was invited to give these talks.
Lattes reached Denmark in early December 1947.54 One evening after a lecture, he was invited to the Carlsberg Mansion, a stately home the well-known
Danish brewery had loaned to Bohr (now a national hero). There, the Brazilian
revealed to Bohr that he wanted to go to the United States because he was sure he
would be able to detect the pi-meson in what was then the biggest particle
accelerator in the world, the 184-inch synchrocyclotron at the University of California’s Radiation Laboratory in Berkeley. Bohr, though, was perplexed by
Lattes’s plans. He asked him why he wanted to leave Bristol precisely when
‘‘things were heating up’’ there, to quote Lattes. Lattes replied that with a bit of
luck, and according to some calculations he had done informally, he was sure he
would be able to identify the pi-meson using that machine.55
Fame
Lattes returned to Brazil at the end of 1947. He married a mathematician, Martha
Siqueira, and they spent their honeymoon in the United States. He had obtained a
grant from the Rockefeller Foundation and went there as an expert consultant of
the US Atomic Energy Commission. Lattes reached Berkeley in early 1948 and
shortly afterwards identified the first pions on plates exposed in the accelerator in
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Fig. 6. Cover of the magazine Science News Letters featuring Lattes and Gardner at the 184’’
synchrocyclotron. Source: Science News Letters.
joint work with US physicist Eugene Gardner (1917–1950), who was then in charge
of the Emulsion Division of the accelerator.56
The press—for instance the New York Times, Time, Life, and Nucleonics
(figure 6)—reported avidly on the artificial production of mesons, most likely
spurred by Lawrence and other members of the board of the Radiation Laboratory.
In Brazil, the news about Lattes and Gardner’s feats in the American media
was exploited to fuel a movement for basic education and exclusive contracts for
lecturing and research work by university professors at the University of Brazil in
Rio de Janeiro. With his blessing, Lattes—‘‘our hero of the Nuclear Era’’—was
used as a figurehead to obtain more government funding for science (figure 7).57
It would not be an overstatement to say that the artificial production of the pimeson at Berkeley triggered a sea change in the Brazilian government’s science
policy.58 To understand the magnitude of the political repercussions—not to
mention the repercussions in the field of science—it is necessary to understand a
little of the science policies in both countries at the time. The synchrocyclotron,
which had been used in World War II to enrich uranium for the atom bomb, was
built under the supervision of American physicist Ernest Lawrence, who raised
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Fig. 7. The Brazilian newspaper A Noite from March 9, 1948, with the headline ‘‘Sensational
discovery by a Brazilian scientist.’’ Lattes appears at the left. Source: A Noite.
around 1.7 million dollars for the project. The objective of the machine was to
produce mesons. Lattes often said that he had never met anyone with such scientific fundraising capacity as Lawrence, due in part to the fact that this Nobel
laureate became a leader of West Coast science in the US and had ready access to
members of the military and the Atomic Energy Commission.
Lattes’s comments make some sense when we see how Lawrence ‘‘sold’’ the
meson to the synchrocyclotron funders:
1)
2)
3)
4)
it would start a new era of intranuclear physics—a reference to the fact that
the particle acts on the inside of the nucleus;
a new source of energy for mankind would probably be found—a highly
appealing promise, especially once the possibility of generating electricity
from nuclear energy started being discussed;
it could be used in cancer treatment, as proved true decades later;
it would be the basis for a ‘‘meson bomb’’—an appeal to the military, even if
nobody could provide much of an explanation of what such a weapon would
be like.59
This in a way justified the considerable sums the government and private sector
channeled into building the machine. The funders included the Rockefeller
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Foundation, the National Academy of Sciences, General Electric, Eastman
Kodak, American Cyanamid, and the Manhattan Project, which had financed and
coordinated the construction of the two atomic bombs dropped on Japan in 1945.
Before Lattes’s arrival, Lawrence and other leaders were in a tight spot: the
accelerator had started working on November 1, 1946, but so far had not produced
any mesons. About ten days after his arrival, Lattes found tracks of mesons in the
emulsions exposed in the accelerator. It is important to note that he did not have
any boxes of Ilford emulsions with him and he did not change anything in the
development method used by Gardner. In Lattes’s words, all he did was to
increase the observation time under the microscope, a position Gardner could not
maintain for very long because he had berylliosis, a disease he had contracted at
age twenty-nine after inhaling beryllium during the building of the atom bomb.60
What happened next was a ‘‘veritable Carnival,’’ to borrow Lattes’s words: press
conferences, newspaper reports, magazine covers, talks—about fifteen in the space
of a few weeks. At the end of 1948, the science section of the New York Times
described the detection of the pi-meson as the most important event in physics that
year.61
Detecting the pi-meson was of itself surely very important. But it is necessary to
also understand it from the broader context. Lawrence saw the achievement as the
catalyst he needed to set a new plan in action: to build a far more powerful
accelerator than the 184-inch synchrocyclotron. In a meeting with the financially
powerful Atomic Energy Commission, he again demonstrated the fundraising
prowess Lattes had already admired. Lawrence told the commission members that
the pi-meson had been detected—even if they probably already knew this—
though he did not yet know why. To answer this question, Lawrence would need a
huge sum of money but felt this outlay would surely be rewarded by the results
that would be obtained by the new machine, the Bevatron: ‘‘the work of Gardner
and Lattes opened the newest new age since the discovery of fission. ‘It might
roughly be compared with the discovery of America.’’’62 Lawrence got what he
asked for, bringing the Radiation Laboratory’s annual budget to levels almost
unimaginable before the artificial production of the pion. Before this, it had languished with around $80,000 a year. In the mid-1950s the Bevatron, built to
produce antiprotons, promptly found them, earning its finders a Nobel prize.
As important as the discovery of the meson by Gardner and Lattes was the
proof that the new technology employed in the 184-inch accelerator worked: the
‘‘phase stability’’ that stopped particles circling in the machine from losing energy.
Indeed, it could be said that this proof is at the root of the countless accelerators of
a larger and smaller scale that then flooded American physics during the following
decade. The Accelerator Era had begun. In appreciation of Lattes’s achievement,
Lawrence offered to donate an accelerator to Brazil—a prototype not being used
at Berkeley—or to teach a group of Brazilian scientists to build a small one, which
would take about a year, according to Lawrence. In a letter, Lattes happily
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reported on the offers, saying that ‘‘the man’’ was very happy with the
ramifications.63
Yet for reasons still unknown, Lawrence’s plans for Brazil never took shape.
They were exchanged by the government for a project headed by the great figure
of Brazilian science at the time, an admiral of the navy, a physicist and chemist,
Álvaro Alberto da Mota e Silva (1889–1976), to build an even more powerful
accelerator than the one at Berkeley. The project was an unmitigated failure. First,
Brazil did not have enough specialized human resources at a time when physics
was already divided, according to Peter Galison, into theoretical, experimental,
and machine building64—this last a category that did not even exist in Brazil. Also,
Brazil did not have the infrastructure needed for such a large (and bold) undertaking. For instance, Brazil did not have a large enough mechanical lathe to
machine the main part for the electromagnet.65
Worse still, the money for the accelerator was spent on horse races by Álvaro
Difini, a professor at the Federal University of Rio Grande do Sul and financial
director of the institution where the project should have been pursued, the Brazilian Center for Physics Research (Centro Brasileiro de Pesquisas Fı́sicas, CBPF),
founded by Lattes and others in 1949. The ‘‘Difini Scandal,’’ as it became known,
was used as political ammunition by the Rio-born journalist and politician Carlos
Lacerda to attack the Brazilian president, Getúlio Vargas. These events had such a
terrible effect on Lattes’s mental health that he moved to the United States to
work and get treatment, seeking to get away from the politically-charged environment. He stayed about two years there, first at the University of Chicago and
then at the University of Minnesota. His scientific output at this time was low—
probably because of the state of his mental health, which included bouts of
depression.66
Back in Brazil, he spent two more years at CBPF—an institution he had helped
to found—and in Rio de Janeiro, a city he had always liked and that ended up
winning its battle with São Paulo for Lattes’s services. Yet it was not long before
Lattes returned to the University of São Paulo, where in 1962 he started a major
collaboration with Japanese physicists called the Brazil-Japan Collaboration for the
study of cosmic radiation using emulsion chambers (‘‘sandwiches’’ of emulsion,
X-ray plates and lead) on Mount Chacaltaya.67 Nevertheless, he stayed just five
years at São Paulo, his departure prompted by a disagreement with a longstanding
colleague and cofounder of CBPF, theoretical physicist Jayme Tiomno
(1920–2011). Tiomno had enrolled for a competition for a tenured position at the
university which had only been set up to provide Lattes with secure employment,
upon which Lattes refused to compete for the post. Other reasons for his decision
involved misunderstandings with colleagues from the Institute of Physics, including
members of the Brazil-Japan Collaboration team. Because of his personality—and
perhaps because of bouts of manic euphoria—Lattes got involved in controversies.
The most famous of them involved his questions about the validity of Einstein’s
theory of relativity. He also questioned the existence of quarks—constituents of
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neutrons and protons—because they could not be detected individually but only in
pairs.68
In February 1949, before leaving Berkeley and returning to Brazil, Lattes had
visited Gardner in the hospital. Reports from the time say that Gardner spent
months in an oxygen tent and kept a microscope and notebook by his side so he
could keep on working. So weak was he that the doctors forbade him from even
holding his baby boy. In November of the following year, Gardner died, aged 37,
hailed in the press as a war hero. In Brazil, Lattes received an honorary doctorate
from the University of São Paulo in 1948. Though he believed that students should
begin research immediately after receiving their undergraduate degree, as he had,
without losing time in graduate studies, now he was Dr. Lattes.
The Expedition
One of Lattes’s first projects on his return to Brazil was to make the laboratory at
Chacaltaya a department of CBPF. Indeed, the following events show that this
marked the beginning of an unprecedented expansion in Brazilian experimental
physics. The behavior of Lattes and his colleagues needs to be seen in context. In
the early 1950s, all around the world high locations were being used to study
particle physics with the help of cosmic radiation. At high altitudes, the likelihood
of capturing a particle from the cosmic-ray shower is far greater than at sea level.69
Therefore, high peaks were an attractive option for two main reasons:
1)
2)
cosmic radiation—itself a natural particle accelerator—was free and therefore
ideal for countries short of the technology and/or financial resources to build
accelerators (which were still challenging from an engineering point of view);
the energy levels cosmic rays reached were—and still are—far higher than
those obtained in an artificial particle accelerator.
From the very simple structure Lattes had encountered on that peak in mid1947—‘‘an easel painted white’’—to the beginning of the following decade, Chacaltaya had been transformed, gaining a global influence. This was thanks not only
to Lattes’s achievements, but also to the Nobel prizes earned by Yukawa and
Powell in 1949 and 1950, respectively. Chacaltaya was high—at an elevation of
about 5,500 meters, or about twice as high as other peaks being used then by
cosmic ray physicists—and its location was favorable, just 30 km from the Bolivian
capital, La Paz, which made the logistics easier. By the mid-1950s, several countries were already doing experiments there, including the USA, the UK, France,
the USSR, India, Japan, Italy, France, and Brazil.
At the end of 1952, CBPF signed an agreement with the University of San
Andrés, one of the longest-lasting agreements in the history of physics in Brazil,
which initiated the creation of the Cosmic Physics Laboratory in Bolivia, approved
formally the previous year. With this, large-scale infrastructure (roads, electricity,
buildings, accommodations, etc.) started to be built at the laboratory, primarily
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thanks to support provided by Brazil and Bolivia.70 Back in Brazil in early 1948,
Lattes, now the scientific director of CBPF, started a project to take a cloud
chamber he had been given by a colleague from the University of Chicago, Marcel
Schein, to Chacaltaya. With financial support from the United Nations Education,
Science and Culture Organization (UNESCO), he managed to bring a team of
specialists to Brazil, including Occhialini and Camerini.
Lattes’s achievements and the beginning of work at Chacaltaya had a cascading
effect on other South American countries.71 We know that a small research group
using nuclear emulsions for the study of cosmic rays (Juan Roederer, Pedro
Waloschek, Beatriz Cougnet—later Beatriz Roederer—and Hans Kobrak) was
formed in March 1949 at the Faculty of Exact Sciences of the University of Buenos
Aires, thanks to contacts the leader of the work, physicist Estrella de Mathov, had
with Wataghin in Brazil.72 We also know that groups working on cosmic rays and/
or emulsions sprang up in other countries in the continent, not just Bolivia, which
hosted the laboratory.73
The scientific expedition to take the cloud chamber to Chacaltaya (figures 8
and 9) at the beginning of the 1950s was an exploit typical of the pre-accelerator
cosmic ray era. It involved different kinds of transport, from trains and trucks to
mule-drawn carts and crossings of extremely dangerous paths and trails. (A brief
film about this adventure has survived.) On Chacaltaya, the cloud chamber never
worked, or, according to the accounts of physicists at the time, worked only briefly,
though there is no consensus as to why.74 Nevertheless, what matters here is the
sudden scaling-up of experimental physics in Brazil after the arrival of the Cosmic
Physics Laboratory.
Fig. 8. Cloud chamber leaving the building of the CBPF in Rio de Janeiro going to Chacaltaya
Mountain in Bolivia in the early 1950s. Credit: Centro Brasileiro de Pesquisas Fı́sicas/Ministério
da Ciência, Tecnologia e Inovação.
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Fig. 9. Bolivian child beside equipment for the cloud chamber taken to Chacaltaya by Brazilian
physicists in the early 1950s. Credit: Centro Brasileiro de Pesquisas Fı́sicas/Ministério da Ciência,
Tecnologia e Inovação.
What was happening at Chacaltaya should be understood in the broader
international context. In the early 1950s, Europe, still shaken after the war, was
trying to rebuild its physics. With little money available and deficient undergraduate physics education, the nuclear emulsion technique proved a winner: not
only was it cheap, but it demanded no sophisticated theoretical or experimental
knowledge. For instance, in Italy, according to Italian experimental physicist Milla
Baldo-Ceolin, the technique was important for the resumption of physics research
after the war.75 In Bristol, soon after Lattes returned to Brazil, balloons started to
be launched, taking particle detectors to great heights; Camerini was one of those
very involved in these experiments. But with the resumption of air traffic, these
initiatives had to be halted. Partly under the influence of Powell, with his Nobel
Prize, some such flights were transferred to Italy as of 1952 for the study of K
mesons. These experiments, which came to be known as the Mediterranean flights,
culminated with the G-Stack (or gigantic stack): a huge pile of emulsion (15 liters)
taken to an altitude of 20 to 30 km.76
One interesting feature of these experiments was the fact that so soon after
World War II they brought together scientists not just from Europe, but also from
the Soviet Bloc. These countries’ involvement owes much to Powell, who believed
in the power of science to unite people across national borders.77 Science was
attempting to unite what politics had sundered and war had destroyed.
Brazil’s ‘‘Big Science’’
Some physics historians see the Mediterranean flights and the G-stack as the
kernels of CERN and Europe’s Big Science, which, given the general scarcity of
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Fig. 10. Headquarters in Chacaltaya (ca. 1970). Credit: The Brazil-Japan Collaboration on
Cosmic Rays/Akinori Ohsawa.
resources for science after the war, had to be developed by joining forces across
national boundaries. CERN itself started in 1954 with 14 founding countries.78 If in
Europe the efforts towards a big scientific project were resolving around a laboratory on land, in Brazil the center of attentions of experimental physics was
Chacaltaya and its Cosmic Physics Laboratory (figure 10). In other words, what
Lattes started ten years earlier when he went to a mountain in the Andes to expose
small boxes with special photographic plates was the seed of our Big Science—
‘‘our’’ in the sense of South American. Before the Cosmic Physics Laboratory,
there was no large-scale experimental physics going on in Brazil or any other
country in South America, as far as we are aware.
Undoubtedly, when we analyze the financial and human resources employed by
Brazil—to focus on just one country—in the experiments on Mount Chacaltaya
(figure 11), we see a significant leap in scale of a size never before seen in the
history of experimental physics in the country. Not only were the cloud chamber
and electronic equipment taken to that peak, but, throughout the existence of the
Brazil-Japan Collaboration, as much as 150 tons of lead as well—part bought in
Bolivia, part in Brazil—and hundreds of thousands of nuclear emulsions and X-ray
films, whose costs Brazil split with Japan at first. The deal was that Brazil would
finance the lead and Japan would cover the emulsions and the plates, but the
Japanese physicists did not obtain the amount of emulsion needed, forcing Lattes
to seek out funding in Brazil.
The first discussions for the Brazil-Japan Collaboration came about at the end
of the 1950s between Lattes and Hideki Yukawa, the theoretical physicist who had
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Fig. 11. Lattes (right), Andrea Wataghin (center), and Ismael Escobar at Chacaltaya in the early
1950s. Credit: Centro Brasileiro de Pesquisas Fı́sicas/Ministério da Ciência, Tecnologia e
Inovação/Acervo Cesar Lattes/SIARQ/Unicamp.
proposed what became the pi-meson and who was encouraged by Japan’s cosmic
ray experiments led by Y. Fujimoto. After some initial upsets—not least because
of the idiosyncrasies of Lattes and his Japanese interlocutor at a meeting in
Moscow in 195979—the agreement was signed after a meeting in Japan also
attended by Occhialini. The first emulsion chamber under the agreement—made
by sandwiching several nuclear emulsions, X-ray plates, and lead plates, covering
an area of around 0.5 square meters—was installed in 1962. The experiment
proceeded for around 30 years.
The X-ray plates were designed initially to enable more high-energy events
(electromagnetic cascades in cosmic radiation) to be observed by the naked eye,
not least because it would be unfeasible to investigate such a large emulsion under
the microscope. It should be repeated that the tracks of the particles were of the
order of thousandths of a millimeter.
Having visually located an electromagnetic cascade of interest—an event—the
track this cascade had taken in the different sandwiches underneath was identified.
This analysis yielded the properties of the cosmic-ray shower and the particle that
had initiated it.*, 80
The Brazil-Japan Collaboration was first set up at the University of São Paulo
and had significant ramifications at CBPF. When Lattes moved to the University
of Campinas in 1967, the work under the collaboration went with him.
Throughout its activities, the Brazil-Japan Collaboration attracted dozens of
Brazilian and Japanese physicists and microscope observers, following the model
conceived by Powell in Bristol two decades earlier, only now to observe nuclear
* In these experiments, fireballs were also discovered—high-energy events involving the
production of many pions—a phenomenon that is not fully understood to this day.
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Phys. Perspect.
emulsions with a large surface area. There are no estimates of how much was spent
on this scheme, but we know, based on statements, that one of the complaints of
physicists from other areas was that it seemed to use ‘‘gold’’ plates rather than lead
ones, alluding to how much of the physics funding in the country went to that
experimental work.*
Finally, it is worth mentioning that in 1964 Lattes spent some time in Italy at the
University of Pisa, where he started a geochronology group, whose work included
dating rocks based on traces left in them as a result of natural radioactivity.81 In
1972, this line of research was begun at the University of Campinas and continues
there and at other Brazilian universities to this day, with applications in the areas
of geology, environmental studies, and oil.
Concluding Remarks
As a scientist, Lattes was undoubtedly a child of the postwar period, at a time
when governments (including Brazil’s) began to realize that knowledge was the
key to political and economic power. To this new relationship, Alexei Kojevnikov
gives the name of the ‘‘metaphysics’’ of the Cold War, referring to the idea that
power was dependent on knowledge.82 About ten years after Brazil’s first physics
gained international recognition—especially Wataghin’s work and Schenberg’s
theoretical work in the early 1940s—Lattes played an important role in Big Science and became Brazil’s ‘‘Hero of the Nuclear Era.’’
Lattes, characteristically modest, used to say that his two great contributions to
physics had been:
1)
2)
adding the chemical element boron to the gelatin on the emulsions, something
that indeed seems to have been crucial for the first detections of the pion at
Bristol;
initiating high-altitude observations on Chacaltaya.83
His research and discoveries not only helped us to understand what things are
made of, but also fostered the development of experimental physics in Brazil and
Latin America, including technologically important developments for the wealth
and well-being of humanity: nuclear energy and medicine.
Lattes worked during the transition from European physics—conducted on a
bench scale with limited resources in dusty labs by individuals or small groups of
scientists—to physics done in giant national and even international laboratories
* Lattes is also in a way linked to the emergence at CBPF of the Radioactivity and Trace
Detection Laboratory—later the Nuclear Trace Laboratory—led by Hervásio de Carvalho,
who became involved in nuclear emulsions probably during a course Lattes gave in 1947 in
Rio de Janeiro at the Mineral Production Laboratory of the Department of Mineral Production, where Guimarães worked. This area of research used nuclear emulsions to study
radioactivity and exposed them in accelerators. One of the laboratory’s specialties was
doping emulsions with radioactive elements.
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Cesar Lattes, Nuclear Emulsions, and the Discovery of the Pi-meson 29
with hundreds or thousands of researchers and fat budgets, part of it coming from
the military establishment. This new way of doing science—Big Science—required
its leaders to have a combination of scientific knowledge along with organizational
and administrative skills.84
Lattes witnessed the transformation of small science into a science that was
far bigger and more complex. In a way, his fame and influence on Brazil’s
scientific policy is partly due to his involvement in formative events in this new
period in physics. Yet he never defended the pursuit of Big Science by Brazil,
and his reasoning was quite pragmatic: the country should pursue physics in a
way that was consistent with its economic reality. He therefore opposed unrealistic plans to build a giant accelerator in the country. He summed up his
position in a pithy phrase: ‘‘We didn’t even know how to make electric light
bulbs.’’85
Lattes allowed his name and achievements to be used politically for the benefit
of a movement whose goal was to build a research base in Brazil, along with
education and exclusive contracts for lecturing and research work by university
professors. As we have seen, he was one of the masterminds of CBPF and he was
instrumental in shaping a political and administrative structure for science in the
country. Science—epitomized at that time by CBPF—was an element of the
Brazilian nation-building project.86
Even with such political support, the movement was not strong enough to
install CBPF inside a university, or perhaps its leaders realized that would not
have been very fruitful because universities at the time were structured into
departments led by professors who had little or no inclination for research. CBPF
was founded as a civil organization as part of a nation-building project. It gradually
became run-down because of a combination of economic factors (inflation and low
wages) and political ones (military coup). By the mid-1970s, one might even say
that CBPF’s main task was to avoid being shut down. When it was turned into
CNPq in the mid-1970s, the institute was reorganized. In the 1980s, when some of
its researchers spent time at the accelerator at Fermilab and, shortly afterwards, at
CERN, the organization again turned its sights abroad, putting an end to a decades-long internal focus.
Lattes remained only a few years at CBPF, whose main building is named after
him. Ironically, his résumé does not contain one single article in which his name is
followed by the acronym CBPF. He moved to the University of São Paulo and
then a few years later to the University of Campinas, where he retired as an
emeritus professor in 1986. Unlike many of his colleagues—Leite Lopes and Tiomno to mention but two—although Tiomno never had a particularly political
profile, he was never persecuted by the military dictatorship.
There are three interpretations of this fact:
1)
without approving of the military regime, he was never far from the centers of
power;
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30
2)
3)
C. L. Vieira and A. A. P. Videira
Phys. Perspect.
the military rulers may have been careful not to attack him because of the
renown and fame he had attained, to avoid negative international repercussions for them;
Lattes was never particularly political in his career, focusing more on science
than what was going on around it.
As yet, there is little new light on this period because the relationship between
Brazilian—or even South American—physicists and dictatorial regimes is only
now beginning to be investigated by physics historians in Brazil.
From the Difini scandal to his death, Lattes’s life was marked by bouts of
depression. His mental health never fully recovered—a fact Lattes never hid, but
which marked (and still marks) him out as a target of prejudice by friends and
colleagues. It spoiled the face of that handsome youth in his early 20s whose
portrait still hangs in the gallery of fame at the University of Bristol, alongside
Nobel prize winners—features that earned him the nickname of enfant terrible at
H. H. Wills—perhaps for the passion he awakened in the girls at Bristol then.
Unhappily, the much sought-after Nobel Prize—even if sought for him more by
others than by Lattes himself—was never forthcoming.* Nonetheless, it is worth
remembering here that Gardner and Lattes’s work was done at a time when the
discovery of a new particle earned its discoverers a Nobel Prize, as in the case of
the antiproton. Lattes’s scientific achievements after the pion were ultimately
outshone. In addition, his public image among professional colleagues was
(unfairly) tainted by his periods of heightened euphoria and depression, which
marked, for instance, one of his last big interviews for a science communication
magazine. In Brazilian physics even now there is just one Lattes. He was what he
was because of two inseparable personality traits that accompanied him forever:
stability and instability. To separate them would be to create a different person. To
break these two traits apart would not help to understand his acts and decisions
throughout his life.
In the words of physicist and physics historian Amélia Hamburger: ‘‘His career
is really very impressive. He carries physics in Brazil.’’87 However, Lattes (really)
* The source of the following information is Ruth Lewin Sime: ‘‘Lattes was nominated in
1949 by Walter Hill of Uruguay, who also nominated Eugene Gardner that year, and he was
nominated by James Holley Bartlett, Jr. of the US, who also nominated Occhialini and
Powell that year. There is no record of either Hill or Bartlett making other nominations.
Occhialini was nominated a total of 7 times: once in 1936, 4 times in 1949, twice in 1950.
Powell received a total of 22 nominations, 8 in 1949, 14 in 1950. It would be interesting to
see if Lattes and the others were nominated in the years after Powell’s prize [1950].’’ E-mail
from Ruth Lewin Sime to C. Leite Vieira dated March 6, 2013. Karl Grandin, director of the
Center for History of Science, Royal Swedish Academy of Sciences, which safeguards the
Nobel archives, has given information about the nominations for Lattes after 1950: ‘‘Lattes
was nominated in 1952, 1953 and 1954 by L. Ruzicka (Zürich). And in 1952 he was also
nominated together with W. Panofsky (Stanford) by Marcel Schein in Chicago.’’ E-mail
from K. Grandin to C. Leite Vieira dated March 25, 2013.
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Cesar Lattes, Nuclear Emulsions, and the Discovery of the Pi-meson 31
believed himself to be less worthy than this. In 1997 on the fiftieth anniversary of
the discovery of the pi-meson, in a telephone interview from his home in Campinas, with one of the authors (CLV), on being asked whether he would change
anything in his life, he replied: ‘‘I did what I could. I was carried by history.’’
Acknowledgments
The authors express their gratitude for funding from FAPERJ (Process E–26/
111.441/2011) and logistical support from the Documentation and Information
Department of the Brazilian Center for Physics Research (Ministry of Science,
Technology, and Innovation). We also acknowledge the support given by Telma
Murari from SIARQ/UNICAMP. The authors thank Edison Shibuya, Ruth Lewin
Sime, Karl Grandin, director of the Center for the History of Science at the Royal
Swedish Academy of Sciences, Donald H. Perkins, Konrad Szczesniak, and Joe
Olmi. This article is part of a project entitled ‘‘O Laboratório de Fı́sica Cósmica de
Chacaltaya—Tentativa brasileira de Big Science?’’ (E–26/111.441/2011—APQ1),
financed by Faperj (Fundação Carlos Chagas Filho de Amparo à Pesquisa do
Estado do Rio de Janeiro). One of us (AAPV) would like to thank the financial
support of CPNq.
References
1
José Reis. ‘‘O fenômeno Lattes,’’ Folha da Manhã March 20, 1948.
2
Fernando de Azevedo, ed., História das Ciências no Brasil (São Paulo: Melhoramentos, 1955), 2
vol.; Simon Schwartzman, A Space for Science: The Development of the Scientific Community in
Brazil (University Park: The Pennylvania State University Press, 1991).
3
Joaquim da Costa Ribeiro, ‘‘A fı́sica no Brasil’’, in de Azevedo (ref. 2), 163–202.
4
Shozo Motoyama, ‘‘A fı́sica no Brasil’’, in M. G. Ferri e S. Motoyama História das ciências no
Brasil (São Paulo: Edusp/EPU, 1979), 61–91.
5
Antonio Augusto Passos Videira, Henrique Morize e o ideal de ciência pura no Brasil na República Velha (Rio de Janeiro: Editora FGV, 2003).
6
Bernhard Gross, ‘‘Lembranças de um fı́sico no Rio de Janeiro (1933–1947),’’ Revista Brasileira de
Ensino de Fı́sica 22 (2000), 266–271. Available at http://www.sbfisica.org.br/rbef/pdf/v22_266.pdf.
7
Sergio Mascarenhas, ‘‘Bernhard Gross and his Contribution to Physics in Brazil,’’ Brazilian
Journal of Physics 29 (1999), 217–219. Available at http://www.scielo.br/pdf/bjp/v29n2/V29_217.
pdf.
8
Antonio Augusto Passos Videira and Martha Cecı́lia Bustamante, ‘‘Gleb Wataghin en la Universidade de São Paulo: un momento culminante de la ciencia brasileña,’’ Quipu 10(3) (1993),
263–284.
9
Ana Maria Ribeiro de Andrade and José Leandro Rocha Cardoso, ‘‘Aconteceu, virou manchete,’’ Revista Brasileira de História 21 (2001), 243–264.
10
José Leite Lopes, ‘‘Guido Beck in Rio de Janeiro,’’ Anais da Academia Brasileira de Ciências 67
(1995), 101–139.
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32
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Phys. Perspect.
11
José Leite Lopes, ‘‘Joaquim Gomes de Souza,’’ in Ciência e Sociedade (1989). Available at
http://cbpfindex.cbpf.br/publication_pdfs/Cs00589.2010_09_06_12_48_34.pdf.
12
Jean Eisenstaedt and Júlio C. Fabris, ‘‘Amoroso Costa e o primeiro livro brasileiro sobre a
Relatividade Geral,’’ Revista Brasileira de Ensino de Fı́sica, 26 (2004), 185–192. Available at http://
www.scielo.br/pdf/rbef/v26n2/a14v26n2.pdf.
13
Nelson Studart, Rogério C.T. da Costa, and Ildeu de Castro Moreira, ‘‘Theodoro Ramos e os
primórdios da Fı́sica Moderna no Brasil,’’ Fı́sica na Escola. 5 (2004), 34–36. Available at http://
www.sbfisica.org.br/fne/Vol5/Num2/v5n1a10.pdf.
14
Martha Cecı́lia Bustamante and Antonio Augusto Passos, ‘‘Bernhard Gross y la fı́sica de los
rayos cósmicos en el Brasil, ‘‘ Quipu 8 (1991), 325–347.
15
Micheline Nussenzveig, Fernando de Souza-Barros and Cássio Leite Vieira, ‘‘Modéstia, ciência
e sabedoria (interview with Cesar Lattes),’’ Ciência Hoje 19 (1995), 11.
16
Nussenzveig, Souza-Barros and Vieira, ‘‘Interview with Cesar Lattes’’ (ref. 15), 11.
17
C. M. G. Lattes, M. Schönberg and W. Schützer, ‘‘Classical Theory of Charged Point-Particles
with Dipole Moments,’’ Anais da Academia Brasileira de Ciências 3(19) (1945), 193–245; C. M. G.
Lattes and G. Wataghin, ‘‘Estatı́stica de partı́culas e núcleons e sua relação com o problema de
abundância dos elementos e seus isótopos,’’ Physics Repport USP 4(17) (1945), 269–269; ‘‘On the
Abundance of Nuclei in the Universe,’’ Physical Review 69 (1946), 237–237.
18
Leonardo Gariboldi, ‘‘Giuseppe Paolo Stanislao Occhialini (1907–1993)—A Cosmic Ray
Hunter from Earth.’’ PhD diss,, Università degli Studi di Milano, 2004.
19
Nussenzveig, Souza-Barros, and Vieira, ‘‘Interview with Cesar Lattes’’ (ref. 15), 13.
20
Cristina Olivotto, ‘‘The Mediterranean Flights and the G-Stack Collaboration (1952–1955): a
first example of European collaboration in particle physics,’’ M. Kokowski, ed., in Proceedings of
the 2nd ICESHS (Cracow: ICESHS, 2006), 490–496.
21
Martha Cecilia Bustamante, ‘‘Giuseppe Occhialini and the History of Cosmic-Ray Physics in
the 1930s: From Florence to Cambridge,’’ in P. Redondi, G. Sironi, P. Tucci and G. Vegni, ed., The
scientific legacy of Beppo Occhialini (Berlin: Springer, 2006), 35–49.
22
Nussenzveig, Souza-Barros, and Vieira, ‘‘Interview with Cesar Lattes’’ (ref. 15), 13.
23
Curriculum Vitae of Cesar Lattes. Original at Arquivo Central do Sistema de Arquivos, State
University of Campinas, São Paulo State, Brazil.
24
Cássio Leite Vieira, ‘‘Um mundo inteiramente novo se revelou: a técnica das emulsões nucleares.’’ PhD diss, Universidade Federal do Rio de Janeiro, 2009. Available at
cienciahoje.uol.com.br/blogues/bussola/arquivos/Livro_tese_cassio…/file; Silke Engler, ‘‘Zur
Geschichte der fotografischen Methode im Kalten Krieg,’’ in Proceedings of the Annual Conference of the German Physical Society, Christian Forstner and Dieter Hoffmann, eds (forthcoming).
We thank Dr. Engler for sending us her work before its publication.
25
T. H. James, ‘‘Why Photography Wasn’t Invented Earlier,’’ in E. Ostroff, ed., Pioneers of
Photography—Their Achievements in Science and Technology (Springfield, VA: SPSE, 1987),
12-17.
26
Ostroff, Pioneers of Photography (ref. 25); Reese Jenkins, ‘‘Some interrelations of Science,
Technology, and the Photographic Industry in the Nineteenth Century.’’ PhD diss, University of
Wisconsin, 1966; Helmut Gernsheim and Alison Gernsheim, History of Photography (Oxford:
Oxford University Press, 1955).
27
T. H. James, ‘‘The Search to Understand Latent Image Formation,’’ in Ostroff, Pioneers of
Photography (ref. 25), 47–58; T. H. James, ed., Theory of the Photographic Process (New York:
MacMillan Publishing Co, 1977).
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Cesar Lattes, Nuclear Emulsions, and the Discovery of the Pi-meson 33
28
Erwin Hiebert, ‘‘The State of Physics at the Turn of the Century,’’ in Mario Bunge and William
L. Shea, eds., Rutherford and the Physics at the Turn of the Century (New York: Dawson and
Science History Publications, 1979), 3–22.
29
Vieira, ‘‘Um mundo inteiramente novo se revelou’’ (ref. 24).
30
C. F. Powell, P. H. Fowler and D. H. Perkins, The Study of Elementary Particles by the Photographic Method: An Account of the Principal Techniques and Discoveries, Illustrated by an Atlas
of Photomicrographs (London: Pergamon Press, 1959).
31
Thomas Schönfeld, ‘‘Aportación al método fotográfico en la fı́sica nuclear: resultados importantes de la investigación de Marietta Blau en Viena (1925–1938),’’ in Brigitte Strohmaier and
Roberst Rosner, ed., Marietta Blau—estrellas de desintegración—biografı́a de pionera de la fı́sica
de partı́culas (México City: Instituto Politécnico, 2006), 171–201.
32
Vieira, ‘‘Um mundo inteiramente novo se revelou’’ (ref. 24), 99.
33
Victor Franz Hess, ‘‘Unsolved Problems in Physics: Tasks for the Immediate Future in Cosmic
Ray Studies,’’ Speech by Austrian physicist Victor Franz Hess on receiving the Nobel Prize in
Physics in 1936. Available at http://nobelprize.org/nobel_prizes/physics/laureates/1936/hesslecture.html. Martha Cecilia Bustamante, ‘‘A descoberta dos raios cósmicos ou o problema da
ionização do ar atmosférico,’’ Revista Brasileira de Ensino de Fı́sica, 35(2) (2013), 603, available at
http://www.sbfisica.org.br/rbef/pdf/352603.pdf.
34
Photographic Emulsion Panels of the Nuclear Physics Sub-Committee, held at Shell Mex
House, London, on Friday 14th February, 1947, at 2:30 pm. Photographic Emulsion Panels of the
Nuclear Physics Sub-Committee, held at Shell Mex House, London, on Tuesday, 16th September,
1947, at 3:00 pm. Photographic Emulsion Panels of the Nuclear Physics Sub-Committee, held at
Shell Mex House, London, on Wednesday 23rd June, 1947, at 2:00 pm. Photographic Emulsion
Panels of the Nuclear Physics Sub-Committee, Report on meeting of the photographic emulsion
panel, held on 21st November, 1947 (report signed by J. Rotblat). Photographic Emulsion Panels
of the Nuclear Physics Sub-Committee, Minutes of the meeting of the photographic emulsion panel
(held at 7th May, 1948, at Liverpool University. The authors wish to thank Dr. L Gariboldi for
copies of the above documents.
35
Don Perkins, ‘‘That Third Pion,’’ in CERN Courier, January 27, 2004, 5.
36
C. M. G. Lattes, P. H. Folwer, and P. Cüer, ‘‘A Study of the Nuclear Transmutations of Light
Elements by the Photographic Method,’’ Proceedings of the Physical Society of London, 59(5)
(1947), 883–900.
37
C. M. G. Lattes, ‘‘My Work in Meson Physics with Nuclear Emulsions,’’ in Laurie M. Brown and
Lillian Hoddeson, ed., The Birth of Particle Physics—Based on a Fermilab Symposium (Cambridge: Cambridge University Press, 1986), 307–310.
38
Leonardo Gariboldi, ‘‘The Reconstruction of Giuseppe Occhialini’s Scientific Bibliography,’’
Atti del XXIII Congresso Nazionale di Storia della Fisica e dell’Astronomia, Bari, 5 a 7 giugno.
Available at www.brera.unimi.it/SISFA/atti/2003/180-189GariboldiBAri.pdf.
39
G. P. S. Occhialini and C. F. Powell, ‘‘Multiple Disintegration Process Produced by Cosmic
Rays,’’ Nature 159 (1947), 93–94.
40
C. M. G. Lattes and G. P. S. Occhialini, ‘‘Determination of the Energy and Momentum of Fast
Neutrons in Cosmic Rays,’’ Nature 159 (1947), 331–332.
41
42
C. F. Powell, Fragments of Autobiography (Bristol: University of Bristol, 1987).
Letter from Peter Fowler (Bristol) to N. McWhirter (London) dated September 2, 1990. Held at
Fowler Papers, Bristol University Special Collections DM 1946/J.55. Reproduced from Gariboldi,
Paolo Stanislao Occhialini (1907–1993), (ref. 18), 126–128.
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43
‘‘Discovery of the Pion—1947,’’ in CERN Courier, June 1997, available at http://fafnir.phyast.
pitt.edu/particles/pion.html.
44
Robert Marshak, Untitled (Interview in four sessions with Charles Weiner for the physics
history project of the Center for History of Physics at the American Institute of Physics), 1970.
Available at http://www.aip.org/history/ohilist/4760_1.html.
45
Jennifer Tucker, ‘‘The Historian, the Picture, and the Archive,’’ Isis 97 (2006), 111–120.
46
D. Perkins, ‘‘The Discovery of the Pion in Bristol in 1947,’’ in Ciência e Sociedade (1997), No.
32—Originally published in the Proceedings of the International School of Physics ‘Enrico Fermi’.
Course CXXXVII (Amsterdam: IOS Press, 1997), 1–11. Available at http://cbpfindex.cbpf.br/
publication_pdfs/CS03297.2010_08_20_16_29_46.pdf.
47
Perkins, ‘‘The Discovery of the Pion’’ (ref. 47).
48
Nussenzveig, Souza-Barros and Vieira, ‘‘Interview with Cesar Lattes’’ (ref. 15), 14–15.
49
Strohmaier and Rosner, ‘‘Marietta Blau’’ (ref. 32).
50
Nussenzveig, Souza-Barros and Vieira, ‘‘Interview with Cesar Lattes’’ (ref. 15), 15.
51
Cesar M. G. Lattes, Giuseppe P. S. Occhialini, Cecil F. Powell, ‘‘Observations on the Tracks of
Slow Mesons in Photographic Emulsions—Part 1,’’ Nature 160 (1947a), 453–456, idem ‘‘Observations on the Tracks of Slow Mesons in Photographic Emulsions. Part 2—Origin of the Slow
Mesons,’’ Nature 160 (1947b), 486–492.
52
Our guess is based on the presence of Hooper and Schaarff at Bohr’s institute, where they
worked on a book with him on cosmic rays. See Nussenzveig, Souza-Barros and Vieira, ‘‘Interview
with Cesar Lattes’’ (ref. 15), 15.
53
Ibid.. Lattes’s arrival is attested by the guest book of the Danish Physical Society.
54
Lattes, ‘‘My Work in Meson Physics with Nuclear Emulsions’’ (ref. 38).
55
Nussenzveig, Souza-Barros and Vieira, ‘‘Interview with Cesar Lattes’’ (ref. 15), 17.
56
José Leite Lopes, ‘‘Cinquenta e cinco Anos de Fı́sica no Brasil: Evocações,’’ CBPF-CS-016/98.
Available at http://cbpfindex.cbpf.br/publication_pdfs/CS01698.2010_08_17_17_43_39.pdf.
57
Ana Maria Ribeiro de Andrade, Fı́sicos, mésons e polı́tica: a dinâmica da ciência na sociedade
(São Paulo/Rio de Janeiro: Hucitec/MAST, 1999).
58
John L. Heilbron, Robert W. Seidel, Bruce R. Wheaton, ‘‘Lawrence and His Laboratory—A
Historian’s View of the Lawrence years’’ (Berkeley: LBNL,1981). Available at http://www.lbl.gov/
Science-Articles/Research-Review/Magazine/1981/.
59
Lattes, ‘‘My Work in Meson Physics with Nuclear Emulsions’’ (ref. 38) and ‘‘War Hero’’
(obituary for Eugene Gardner), Time December 11, 1950. Berylliosis stiffens the lungs, making
breathing difficult.
60
New York Times, ‘‘Artificial Cosmic Rays’’. March 11, 1948, 26.
61
http://www.lbl.gov/Science-Articles/Research-Review/Magazine/1981/81fepi3.html.
62
Also: http://www.aip.org/history/lawrence/cws.htm ‘‘Meanwhile Congress took nuclear research
from military control and gave it to the civilian Atomic Energy Commission. Lawrence had
lobbied the AEC to support the construction of even bigger accelerators, convincing them the
results would be worth the huge expense. But the Berkeley team faced competition from a
collection of scientists in the northeastern states. In 1947, they founded the Brookhaven National
Laboratory on Long Island in New York and asked the AEC for their own accelerator. After
several rounds of proposals and counter proposals, the AEC agreed to support new proton synchrotrons at both labs. Brookhaven would build quickly to reach 3 BeV (a BeV, now called a
GeV, is a billion electric volts). Berkeley aimed to construct a 6 BeV machine with a 10,000 ton
magnet, the ‘‘Bevatron.’’
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63
Letter from Cesar Lattes to José Leite Lopes. Lattes_CX01_File 01_10(1–2). AC/SIARQ/
UNICAMP. We wish to thank archivist Telma Murari for the kindness she showed us in
Campinas.
64
Peter L. Galison, Image and Logic (Chicago: University of Chicago Press, 1997).
65
Ana Maria Ribeiro de Andrade, ‘‘Fı́sicos, mésons e polı́tica’’ (ref. 58) and Carlos Alberto dos
Santos, ‘‘O sincrocı́clotron do CNPq: da concepção ao abandono’’, Revista Brasileira de Ensino de
Fı́sica 35 (2013), 1607–1620. Available at http://www.sbfisica.org.br/rbef/pdf/351607.pdf.
66
Alfredo Marques de Oliveira, ‘‘Em memória de Cesar Lattes,’’ CBPF-CS-004/05. Available at
http://cbpfindex.cbpf.br/publication_pdfs/cs00405.2010_08_11_13_04_39.pdf.
67
Cássio Leite Vieira and Antonio A.P. Videira, ‘‘O papel das emulsões nucleares na institucionalização da pesquisa em fı́sica experimental no Brasil,’’ Revista Brasileira de Ensino de Fı́sica, 33
(2011), 2603–2607. Available at http://www.sbfisica.org.br/rbef/pdf/332603.pdf.
68
Statement given by Cesar Lattes to Maria de Lourdes Fávero and Ana Elisa Gerbasi da Silva
(1990), Proedes Archives/UFRJ, unpublished. We thank Dr. Maria de Lourdes Fávero for
assigning us a copy of this interview. See also the personal statement by Edison Shibuya to
Antonio A. P. Videira, Campinas, May 12, 2012, and José Hamilton Ribeiro. ‘‘Cesar Lattes, Gênio
ou Louco,’’ Brasil Século 21(3) (2012), 48–55.
69
Serge Korff, ‘‘High Altitude Laboratories,’’ Physics Today 2(11) (1950), 17–23.
70
Ana Maria Ribeiro de Andrade, ‘‘Os Raios Cósmicos entre a ciência e as relações internacionais’’, in Ciência, Polı́tica e Relações Internacionais, Marcos Chor Maio, ed., (Rio de Janeiro:
FIOCRUZ/Edições UNESCO, 2005), 215–242.
71
Letter from Guido Beck to José Leite Lopes. Leite Lopes, ‘‘Guido Beck in Rio de Janeiro’’ (ref.
10), 18. Also available at http://cbpfindex.cbpf.br/publication_pdfs/cs02497.2010_08_20_12_58_11.
pdf.
72
Juan G. Roederer, ‘‘Early Cosmic Ray Research in Argentina,’’ Physics Today 65(1) (2003),
32–37.
73
Laboratório Brasileiro de Pesquisas Cósmicas nos Andes, Diário de Notı́cias (Rio de Janeiro),
February 21, 1952, 1.
74
Fernando de Souza Barros, ‘‘O CBPF e o Laboratório de Chacaltaya’’, in Amós Troper,
Antonio A. P. Videira and Cássio L. Vieira, eds., Os 60 anos do CBPF e a Gênese do CNPq (Rio
de Janeiro: CBPF, 2010), 165–180.
75
Milla Baldo-Ceolin ‘‘The Discreet Charm of the Nuclear Emulsion Era,’’ Annual Review of
Nuclear and Particle 52, (2002), 1–21.
76
Olivotto, ‘‘The Mediterranean Flights’’ (ref. 20).
77
Ibid.
78
Ibid.
79
Personal statement given by Edison Shibuya to Antonio A. P. Videira in Campinas on May 22,
2012.
80
Cesar M. G. Lates, Yochi Fujimoto and Shun-iti Hasegawa, ‘‘Hadronic Interactions of High
Energy Cosmic-Ray Observed by Emulsion Chambers,’’ Physics Reports 65 (1980), 151–229.
81
Giulio Bigazzi and Jorge C. Hadler Neto, ‘‘Cesar Lattes: a Pioneer of Fission Track Dating’’, in
Alfredo Marques, ed., Cesar Lattes 70 Anos—A Nova Fı́sica Brasileira (Rio de Janeiro: Centro
Brasileiro de Pesquisas Fı́sicas, 1994), 124–150.
82
Alexei B. Kojevnikov, Stalin’s Great Science: The Times and Adventures of Soviet Physicists
(London: Imperial College Press, 2004), 300.
Author's personal copy
36
C. L. Vieira and A. A. P. Videira
Phys. Perspect.
83
Concerning the choice of the best site to exposure the plates, Perkins many years later wrote: ‘‘I
had asked [in 1946] G. P. [Thomson] about the possibility of very high mountain exposures,
specifically at Chacaltaya in Bolivia. He told in no uncertain terms that he was not providing
support for research students to go half way round the world. I should just get a map of Europe
and find an alp!’’ Donald H. Perkins, ‘‘Some notes on the historical development of nuclear
emulsions,’’ unpublished manuscript sent to one of us (CLV).
84
Peter Galison and Bruce Hevly, eds., in Big Science—The Growth of Large-Scale Research
(Stanford: Stanford University Press, 1992).
85
Statement given by Cesar Lattes to Ana Maria Ribeiro de Andrade in Ana Maria Ribeiro de
Andrade and Érika Werneck, ‘‘Mésons, prótons, era uma vez acelerador’’ (DVD, Rio de Janeiro,
MAST, 1996).
86
José Leite Lopes, ‘‘Cesar Lattes, O Centro Brasileiro de Pesquisas Fı́sicas e a Nova Fı́sica no
Brasil,’’ in Alfredo Marques, ed., Cesar Lattes 70 Anos—A Nova Fı́sica Brasileira (Rio de Janeiro:
Centro Brasileiro de Pesquisas Fı́sicas, 1994), 70–87, letter mentioned on page 79.
87
Amélia I. Hamburger, ‘‘Cesar Lattes, fı́sico brasileiro,’’ Revista USP 66 (2005), 132–138.
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